CASE STUDY: RIVERVIEW PARK ECOSYSTEM RESTORATION
PROBLEM: Construction of a new ecosystem focused learning and interpretive center located at the riverside of the Green River in Kent, WA required construction of a new secondary channel, resulting in the creation of a mid-stream island.
SOLUTION: In order to stabilize the newly constructed secondary river channel a wrap-faced slope construction method was utilized on the lower slopes with a Coir 900 erosion control mat and PermeaTex 2200 woven geotextile. Upper slopes were stabilized with PermeaTex C2 Bio-Net erosion control matting.
CONSTRUCTION DETAILS: The wrap-faced slope construction method involves placement of both Coir 900 and PermeaTex 2200 materials in each lift. First the Coir 900 is laid out, with the PermeaTex 2200 placed over the top. Structural fill is placed to an 18” depth, it is held back 12” from the final face location. The PermeaTex 2200 is folded over the structural fill and construction on the bullnose is started. A compost/ topsoil blend is placed in front 12” of the wrap, the Coir 900 is then wrapped and folded over the face. Placement of PermeaTex 2200 and Coir 900 is done for the next lift and the technique is repeated until the desired final elevation is achieved. On the upper slopes PermeaTex C2 is utilized for soil stabilization. First, the anchor trench is excavated, the matting is placed in the trench, stapled to the bottom, backfilled and folded over the top, and stapled again to adequately secure the matting at the top of the slope. The matting material is rolled down the slope, if a mid-slope seam is encountered the material is to be shingled with the upslope mat shingling over the top of the downslope portion. Side-by-side seams are overlapped 3-6” and stapled. All erosion control matting is stapled to ensure consistent contact with the soil. Use of 6” bright-wire staples fastened the matting. These were preferred as they begin oxidation once placed in the soil, the oxidation process results in pull-out resistance and eventual complete oxidation and disappearance of staples.
- PermeaTex C2 Bio-Net—3,600 SY
- PermeaTex Coir 900—7,200 SY
- PermeaTex 2200 Woven Geotextile— 2,400 SY